Some spectral resources, such as carrier frequencies, may be licensed to users with different access priorities to the spectral resources. Some users may be allowed to use the spectral resources until a higher priority user claims the spectral resources, at which point the lower priority user must stop using the claimed spectral resources and may continue communicating on unclaimed spectral resources, if available.
For example, in the United States, the Federal Communications Commission (FCC) has opened 150 Megahertz (MHz) of shared spectrum at 3.5 Gigahertz (GHz) for lightly licensed, shared used as a “Citizens Broadband Radio Service” (CBRS). The method(s), function(s), and/or technique(s) described herein may also be applied to other frequency bands. The CBRS attempts to improve the use of increasingly scarce spectrum through sharing by different user groups. In CBRS the three groups include three tiers of users, ordered from the highest priority to the lowest priority: Incumbent Access, Priority Access License (PAL), and General Authorized Access (GAA). The FCC specifies that a Spectrum Access System (SAS) entity must protect the higher priority users from interference by the lower priority users (protecting Incumbent Access from interference by PAL and GAA, and protecting PAL from interference by GAA). A user, which may include a base station (such as an Enhanced Node B or eNB) serving user equipments, may be required to shift to a different carrier frequency when an Incumbent Access entity or a Priority Access License entity claims the carrier frequency that the base station is using to serve the user equipments, when the SAS entity decides that the base station needs to switch to a different carrier frequency by way of interference margin partitioning and redistribution, or when an existing traffic load changes and the SAS entity instructs two different base stations to swap carrier frequencies to improve interference margins. It may be difficult for the base station to switch carrier frequencies while continuing to serve the user equipments.